scholarly journals First Report of Stigmina lautii in the United States

Plant Disease ◽  
2002 ◽  
Vol 86 (6) ◽  
pp. 699-699
Author(s):  
C. S. Hodges
Keyword(s):  
United States ◽  
North Carolina ◽  
Plant Disease ◽  
The United States ◽  
New Host ◽  
Decay Fungi ◽  
First Report ◽  
Blue Spruce ◽  
Western North Carolina ◽  
Needle Blight

In June 1999, a specimen of blue spruce (Picea pungens) from Avery County, North Carolina, exhibiting symptoms of needle blight was submitted to the Plant Disease and Insect Clinic at North Carolina State University. A fungus sporulating profusely on symptomatic needles was identified as Stigmina lautii. Since then, three additional specimens have been received—on blue spruce from Ashe County, on Norway spruce (P. abies) from Avery County, and on Picea sp. from Cherokee County. These counties are all in western North Carolina but are not contiguous, indicating that the fungus is probably widespread in the western part of the state. S. lautii was described by Sutton (2) in 1973 on black spruce (P. mariana) and white spruce (P. glauca) collected from various locations in Manitoba and Saskatchewan, Canada. The only other reference found to the fungus is a specimen collected in British Columbia, Canada, on P. glauca in 1972 (2). The morphology of the North Carolina specimens of S. lautii is essentially as described by Sutton. The dark brown, superficial, flattened sporodochia are developed only through stomata. Sporodochia are found both on symptomatic needles as well as on adjacent green needles. Conidiophores arise only laterally from the lower, outer cells of the sporodochium, and are macronematous, mononematous, brown, smooth, unbranched, 1 to 2 septate, and 10 to 20 × 4 to 6 μm. Conidiogenous cells are brown, monoblastic, integrated, terminal, percurrent with 3 to 4 annelations, and 6 to 12 × 4 to 5 μm. Conidia are pale brown, cylindrical to fusiform, often curved, thick walled, verrucose, 5 to 8 distoseptate, and 25 to 45 × 5 to 6 μm. Superficially, the sporodochia of S. lautii might be confused with pycnidia of Rhizosphaera kalkhoffii, which also arise through stomata. The latter fungus also is associated with a needle blight of Picea spp. in western North Carolina. Both fungi were present on one specimen examined. Currently, no information is available on the pathogenicity of S. lautii, but its association with typical needle blight symptoms and the known pathogenicity of other Stigmina spp. on conifers make it likely that the fungus is pathogenic to spruce. To my knowledge, this is the first report of S. lautii in the United States, and P. pungens and P. abies represent new host records for the fungus. Specimens BPI 747910 and 840959, have been deposited in the herbarium of the National Fungus Collections, Beltsville, MD. References: (1) J. H. Ginns. Page 158 in: Compendium of Plant Disease and Decay Fungi in Canada 1960-1980. Agric. Can. Publ. 1813, 1986. (2) B. C. Sutton. Mycol. Pap. 132:113, 1973.

scholarly journals First Report of Stem Blight Caused by Calonectria colhounii (Anamorph Cylindrocladium colhounii) on Greenhouse-Grown Blueberries in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1187-1187
Author(s):  
J. J. Sadowsky ◽  
T. D. Miles ◽  
A. M. C. Schilder
Keyword(s):  
United States ◽  
North Carolina ◽  
Root Rot ◽  
The United States ◽  
Vaccinium Corymbosum ◽  
Conidial Suspension ◽  
Centraalbureau Voor ◽  
First Report ◽  
Stem Lesions ◽  
Β Tubulin

Necrotic stems and leaves were observed on 2- to 4-month-old, rooted microshoot plants (Vaccinium corymbosum L. ‘Liberty’ and ‘Bluecrop’, V. angustifolium Aiton ‘Putte’, and V. corymbosum × V. angustifolium ‘Polaris’) in a Michigan greenhouse in 2008 and 2009. As the disease progressed, leaves fell off and 80 to 100% of the plants died in some cases. Root rot symptoms were also observed. A fungus was isolated from stem lesions. On potato dextrose agar (PDA), cultures first appeared light tan to orange, then rusty brown and zonate with irregular margins. Chains of orange-brown chlamydospores were abundant in the medium. Macroconidiophores were penicillately branched and had a stipe extension of 220 to 275 × 2.5 μm with a narrowly clavate vesicle, 3 to 4 μm wide at the tip. Conidia were hyaline and cylindrical with rounded ends, (1-)3-septate, 48 to 73 × 5 to 7 (average 60 × 5.5) μm and were held together in parallel clusters. Perithecia were globose to subglobose, yellow, 290 to 320 μm high, and 255 to 295 μm in diameter. Ascospores were hyaline, 2- to 3-septate, guttulate, fusoid with rounded ends, slightly curved, and 30 to 88 × 5 to 7.5 (average 57 × 5.3) μm. On the basis of morphology, the fungus was identified as Calonectria colhounii Peerally (anamorph Cylindrocladium colhounii Peerally) (1,2). The internal transcribed spacer region (ITS1 and ITS2) of the ribosomal DNA and the β-tubulin gene were sequenced (GenBank Accession Nos. HQ909028 and JF826867, respectively) and compared with existing sequences using BLASTn. The ITS sequence shared 99% maximum identity with that of Ca. colhounii CBS 293.79 (GQ280565) from Java, Indonesia, and the β-tubulin sequence shared 97% maximum identity with that of Ca. colhounii CBS 114036 (DQ190560) isolated from leaf spots on Rhododendron sp. in North Carolina. The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 129628). To confirm pathogenicity, 5 ml of a conidial suspension (1 × 105/ml) were applied as a foliar spray or soil drench to four healthy ‘Bluecrop’ plants each in 10-cm plastic pots. Two water-sprayed and two water-drenched plants served as controls. Plants were misted intermittently for 2 days after inoculation. After 7 days at 25 ± 3°C, drench-inoculated plants developed necrotic, sporulating stem lesions at the soil line, while spray-inoculated plants showed reddish brown leaf and stem lesions. At 28 days, three drench-inoculated and one spray-inoculated plant had died, while others showed stem necrosis and wilting. No symptoms were observed on control plants. Fungal colonies reisolated from surface-disinfested symptomatic stem, leaf, and root segments appeared identical to the original isolate. Cy. colhounii was reported to cause a leaf spot on blueberry plants in nurseries in China (3), while Ca. crotalariae (Loos) D.K. Bell & Sobers (= Ca. ilicicola Boedijn & Reitsma) causes stem and root rot of blueberries in North Carolina (4). To our knowledge, this is the first report of Ca. colhounii causing a disease of blueberry in Michigan or the United States. Because of its destructive potential, this pathogen may pose a significant threat in blueberry nurseries. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) L. Lombard et al. Stud. Mycol. 66:31, 2010. (3) Y. S. Luan et al. Plant Dis. 90:1553, 2006. (4) R. D. Milholland. Phytopathology 64:831, 1974.

scholarly journals First Report of Pseudoperonospora cubensis Causing Downy Mildew on Momordica balsamina and M. charantia in North Carolina

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1279-1279 ◽  
Author(s):  
E. Wallace ◽  
M. Adams ◽  
K. Ivors ◽  
P. S. Ojiambo ◽  
L. M. Quesada-Ocampo
Keyword(s):  
United States ◽  
North Carolina ◽  
Downy Mildew ◽  
Leaf Surface ◽  
The United States ◽  
Pseudoperonospora Cubensis ◽  
Post Inoculation ◽  
Bitter Melon ◽  
First Report ◽  
C Cycle

Momordica balsamina (balsam apple) and M. charantia L. (bitter melon/bitter gourd/balsam pear) commonly grow in the wild in Africa and Asia; bitter melon is also cultivated for food and medicinal purposes in Asia (1). In the United States, these cucurbits grow as weeds or ornamentals. Both species are found in southern states and bitter melon is also found in Pennsylvania and Connecticut (3). Cucurbit downy mildew (CDM), caused by the oomycete Pseudoperonospora cubensis, was observed on bitter melon and balsam apple between August and October of 2013 in six North Carolina sentinel plots belonging to the CDM ipmPIPE program (2). Plots were located at research stations in Johnston, Sampson, Lenoir, Henderson, Rowan, and Haywood counties, and contained six different commercial cucurbit species including cucumbers, melons, and squashes in addition to the Momordica spp. Leaves with symptoms typical of CDM were collected from the Momordica spp. and symptoms varied from irregular chlorotic lesions to circular lesions with chlorotic halos on the adaxial leaf surface. Sporulation on the abaxial side of the leaves was observed and a compound microscope revealed sporangiophores (180 to 200 μm height) bearing lemon-shaped, dark sporangia (20 to 35 × 10 to 20 μm diameter) with papilla on one end. Genomic DNA was extracted from lesions and regions of the NADH dehydrogynase subunit 1 (Nad1), NADH dehydrogynase subunit 5 (Nad5), and internal transcribed spacer (ITS) ribosomal RNA genes were amplified and sequenced (4). BLAST analysis revealed 100% identity to P. cubensis Nad1 (HQ636552.1, HQ636551.1), Nad5 (HQ636556.1), and ITS (HQ636491.1) sequences in GenBank. Sequences from a downy mildew isolate from each Momordica spp. were deposited in GenBank as accession nos. KJ496339 through 44. To further confirm host susceptibility, vein junctions on the abaxial leaf surface of five detached leaves of lab-grown balsam apple and bitter melon were either inoculated with a sporangia suspension (10 μl, 104 sporangia/ml) of a P. cubensis isolate from Cucumis sativus (‘Vlaspik' cucumber), or with water as a control. Inoculated leaves were placed in humidity chambers to promote infection and incubated using a 12-h light (21°C) and dark (18°C) cycle. Seven days post inoculation, CDM symptoms and sporulation were observed on inoculated balsam apple and bitter melon leaves. P. cubensis has been reported as a pathogen of both hosts in Iowa (5). To our knowledge, this is the first report of P. cubensis infecting these Momordica spp. in NC in the field. Identifying these Momordica spp. as hosts for P. cubensis is important since these cucurbits may serve as a source of CDM inoculum and potentially an overwintering mechanism for P. cubensis. Further research is needed to establish the role of non-commercial cucurbits in the yearly CDM epidemic, which will aid the efforts of the CDM ipmPIPE to predict disease outbreaks. References: (1) L. K. Bharathi and K. J. John. Momordica Genus in Asia-An Overview. Springer, New Delhi, India, 2013. (2) P. S. Ojiambo et al. Plant Health Prog. doi:10.1094/PHP-2011-0411-01-RV, 2011. (3) PLANTS Database. Natural Resources Conservation Service, USDA. Retrieved from http://plants.usda.gov/ , 7 February 2014. (4) L. M. Quesada-Ocampo et al. Plant Dis. 96:1459, 2012. (5) USDA. Index of Plant Disease in the United States. Agricultural Handbook 165, 1960.

scholarly journals First Report of Tobacco ringspot virus in Blackberry (Rubus sp.) in Alabama

Plant Disease ◽  
2008 ◽  
Vol 92 (12) ◽  
pp. 1708-1708 ◽  
Author(s):  
E. Coneva ◽  
J. F. Murphy ◽  
R. Boozer ◽  
N. Velásquez
Keyword(s):  
United States ◽  
North Carolina ◽  
South Carolina ◽  
Virus Infection ◽  
The United States ◽  
Negative Control ◽  
Ringspot Virus ◽  
First Report ◽  
Tobacco Ringspot Virus ◽  
Control Samples

In 2006, primocane stunted growth and crumbly berry development were observed on 4-year-old Kiowa and Apache blackberry cultivars grown at the Chilton Research and Extension Center, Clanton, AL. Samples from affected plants were tested for virus infection by ELISA kits (Agdia, Inc., Elkhart, IN) specific to each of 14 different viruses. Most samples tested positive for Tobacco ringspot virus (TRSV). TRSV was detected in blackberry samples from North Carolina and South Carolina (2). Bray et al. (1) studied the incidence of viruses in blackberry nursery stock in the United States and reported that 9% of the tested samples contained TRSV. Thus, a survey was conducted for TRSV incidence among commercial blackberry stands in eight counties in Alabama during July 2007. Blackberry plants were observed to express virus-like symptoms including chlorotic spots on leaves, leaf veinal chlorosis, stunting, and combinations thereof. Fruit-bearing plants sometimes had crumbly fruit symptoms characteristic of virus infection. Leaf samples that were collected from symptomatic and nonsymptomatic plants representing 14 cultivars were tested by TRSV ELISA (Agdia, Inc.). Of 180 blackberry samples, 68 tested positive for TRSV. Positive ELISA reactions for TRSV were on average 28 times greater than the reactions of known negative control samples considered negative for TRSV. Blackberry plants shown to be infected with TRSV during the 2007 survey were tested in July 2008 in an effort to confirm the presence of TRSV. Fifty-four percent of the samples tested positive by ELISA with the average positive ELISA value being 21 times higher than the average negative ELISA value for known negative control samples. To further confirm the occurrence of TRSV in Alabama-grown blackberry plants, leaf samples were tested by reverse transcription (RT)-PCR to amplify a 329-bp fragment of the viral coat protein gene (TRSV RNA 2 sequence accession no. NC_005096; primers TRSCP-F (5′-TCTGGCACTATAAGCGGAAG-3′) and TRSCP-R (5′-GAAAACATGGGAGGATGCAC-3′). A single band of the anticipated size was amplified (analyzed by agarose gel electorphoresis and visualized by ethidium bromide staining) from RNA samples extracted with a RNeasy Mini kit (Qiagen, Valencia, CA) from blackberry samples that tested positive for TRSV by ELISA and a known positive control. No amplified product resulted from a blackberry sample that tested negative for TRSV by ELISA. These results illustrate and confirm the presence of TRSV in blackberry leaf tissues grown in Alabama. To our knowledge, this is the first report of TRSV infection of blackberry plants in Alabama. References: (1) M. M. Bray et al. HortScience 40:874, 2005. (2) T. L. Guzmán-Baeny. Incidence, distribution, and symptom description of viruses in cultivated blackberry (Rubus subgenus Eubatus) in the southeastern United States. M.S. thesis, North Carolina State University, Raleigh, 2003.

scholarly journals First Report of Curvularia Blight of Zoysiagrass Caused by Curvularia lunata in the United States

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 173-173 ◽  
Author(s):  
J. A. Roberts ◽  
L. P. Tredway
Keyword(s):  
United States ◽  
North Carolina ◽  
Morphological Characteristics ◽  
Microscopic Analysis ◽  
The United States ◽  
Curvularia Lunata ◽  
One Pot ◽  
Plastic Container ◽  
First Report ◽  
Initial Symptoms

Symptoms of an unknown foliar blight have been observed in zoysiagrass (Zoysia matrella, Z. japonica, and hybrids) landscapes in North Carolina since 2002. Disease activity is most common during spring and summer when temperatures are between 21 and 30°C. Affected leaves initially exhibit small, chocolate brown spots, followed by dieback of leaves from the tips, and eventually blighting of entire tillers. Symptoms appear in small, irregular patches as much as 15 cm in diameter, but numerous patches may coalesce to impact large sections of turf. Infected turf appears tan or brown from a distance, but often turns black during periods of wet or humid weather. Microscopic analysis revealed profuse sporulation of Curvularia spp. on the surface of symptomatic leaves. Leaf sections were surface disinfested in 10% Clorox for 1 to 2 min, blotted dry, then plated on potato dextrose agar (PDA) containing 50 mg/l of tetracycline, streptomycin, and chloramphenicol. Twenty-eight fungal isolates were obtained from six locations. Examination of conidia produced in culture revealed 21 isolates of Curvularia, two isolates of Drechslera, one isolate of Nigrospora, and four unidentified sterile fungi. Curvularia isolates were identified to species on the basis of morphological characteristics (1) and ITS-rDNA sequences. Known isolates of C. eragrostidis, C. geniculata, C. inequalis, C. lunata, C. pallescens, and C. trifolii were obtained from the American Type Culture Collection for comparison. All unknown isolates produced conidia that were characteristic of C. lunata (lacking a protuberant hilum, smooth walled, tri-septate, predominantly curved, and mid- or dark brown, average dimensions 17 to 25 × 8 to 12 μm). Colonies on PDA lacked stroma or the zonate appearance indicative of C. lunata var. aeria. The pathogenicity of C. lunata isolates was tested on zoysiagrass cvs. El Toro (Z. japonica) and Emerald (Z. japonica × matrella). Cores (11.4 cm in diameter) of established zoysiagrass were potted in calcined clay (Turface Allsport; Profile Products LLC, Buffalo Grove, IL), and transferred to a greenhouse where the average temperature was 26°C. Five isolates were selected to represent the geographic range of Curvularia blight in North Carolina, and conidia were produced on PDA under continuous fluorescent illumination. Each isolate was inoculated to one pot of each zoysiagrass variety by spraying with 25 ml of a suspension containing 2 × 105 conidia/ml with an airbrush. Inoculated pots were placed in a sealed, nontransparent plastic container for 48 h at 28°C to encourage infection and then transferred back to the greenhouse bench. Pathogenicity tests were repeated four times over time. Isolates ZFB3 and ZFB28 were most virulent with initial symptoms of foliar dieback appearing within 1 week after inoculation. Continued disease progress resulted in necrosis of the entire plant. Other isolates induced symptoms within 2 to 3 weeks after inoculation; however, disease severity was lower as compared with ZFB3 and ZFB28 throughout each experiment. Cvs. Emerald and El Toro were equally susceptible to infection by C. lunata. To our knowledge, this is the first report of Curvularia blight of zoysiagrass in the United States. This disease was previously described in Japan where it is commonly referred to as ‘dog footprint’ (3) and Brazil (2). References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) F. B. Rocha et al. Australas. Plant Pathol. 33:601, 2004. (3) T. Tani and J. B. Beard. Color Atlas of Turfgrass Diseases. Ann Arbor Press, Chelsea, MI, 1997.

scholarly journals Sensitivity of Isolates of Phytophthora capsici from the Eastern United States to Fluopicolide

Plant Disease ◽  
2011 ◽  
Vol 95 (11) ◽  
pp. 1414-1419 ◽  
Author(s):  
Anthony P. Keinath ◽  
Chandrasekar S. Kousik
Keyword(s):  
United States ◽  
North Carolina ◽  
South Carolina ◽  
Mycelial Growth ◽  
Phytophthora Capsici ◽  
The United States ◽  
Eastern United States ◽  
Baseline Sensitivity ◽  
First Report ◽  
Zoospore Production

Fluopicolide, a pyridinylmethyl-benzamide fungicide, was registered in the United States in 2008 to control diseases caused by Oomycete pathogens, such as Phytophthora capsici, on cucurbit and solanaceous vegetables. The main objective of this study was to determine baseline sensitivity to fluopicolide in isolates of P. capsici from the southeastern and midwestern United States. A total of 69 isolates from Florida (14 isolates), Georgia (14 isolates), Michigan (24 isolates), North Carolina (3 isolates), and South Carolina (17 isolates) that had not been previously exposed to fluopicolide were grown on fungicide-amended medium to determine sensitivity of mycelia, sporangia, and zoospores to the fungicide. All isolates of P. capsici tested (range of 54 to 69 isolates per assay) were sensitive to fluopicolide in all four assays. The median EC50 fluopicolide concentration was 0.22, 2.08, 0.048, and 0.10 mg/liter in the mycelial growth, zoospore germination, sporangia production, and zoospore production assays, respectively. For mycelial growth and zoospore germination, isolates from Michigan had a higher mean EC50 value than isolates from the four southeastern states. This is the first report of variation in baseline sensitivity to a fungicide by P. capsici isolates from different regions of the United States. In the sporangia production and zoospore production assays, isolates from different states did not differ in sensitivity. Single rates of fluopicolide were tested with additional isolates to validate discriminatory rates for monitoring sensitivity. A concentration of 0.3 or 1.0 mg/liter is recommended for mycelial growth, and 0.1 mg/liter is recommended for sporangia and zoospore production.

scholarly journals First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Erythrina herbacea (Coral Bean)

Plant Disease ◽  
2008 ◽  
Vol 92 (10) ◽  
pp. 1472-1472 ◽  
Author(s):  
A. J. Gevens ◽  
N. Nequi ◽  
A. Vitoreli ◽  
J. J. Marois ◽  
D. L. Wright ◽  
...  
Keyword(s):  
United States ◽  
Rust Fungus ◽  
Lima Bean ◽  
The United States ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Rust Disease ◽  
New Host ◽  
First Report ◽  
Scarlet Runner Bean

Soybean rust (SBR), caused by the obligate fungus Phakopsora pachyrhizi Syd. & P. Syd., was initially reported on soybean (Glycine max L.) in Louisiana in 2004 and has since been reported on soybean and/or kudzu (Pueraria lobata (Willd.) Ohwi) in 9 states in 2005, 15 states in 2006, and 19 states in 2007 (1). The host range of P. pachyrhizi includes plants that are all in the Fabaceae or legume family. Six plant species in the United States have been reported as hosts of P. pachyrhizi: soybean, kudzu, Florida beggarweed (Desmodium tortuosum (Sw) DC.), dry bean (Phaseolus vulgaris L.), lima bean (P. lunatus L.), and scarlet runner bean (P. coccineus L.) (4). On 17 April 2008, a rust disease was observed on a weedy legume host with red showy flowers that was growing with kudzu in an overgrown vacant lot in the understory of live oak trees (Quercus virginiana Mill.) in Citra, FL. The discovery was made during routine scouting of this Integrated Pest Management Pest Information Platform for Extension and Education (IPM PIPE) mobile sentinel plot (3). The plant was confirmed by University of Florida botanists to be Erythrina herbaceae L., commonly known as coral bean. Coral bean is native to the southeastern United States and also is planted as a perennial ornamental. A sample of leaves exhibiting rust pustules characteristic of P. pachyrhizi uredinia was collected and examined with a microscope. Brown-to-brick red, angular lesions that were 3 to 11 mm in diameter (average 6.75 mm) were observed on the undersides of the leaves of two trifoliates. Within these lesions, there were several uredinia, some exuding hyaline, echinulate urediniospores (20 × 25 μm). The visual diagnosis and the species of the rust fungus were confirmed to be P. pachyrizi by a real-time PCR protocol (2). The diagnosis on this new host was verified by a USDA, APHIS National Mycologist in Beltsville, MD. Coral bean may serve as an additional overwintering host for P. pachyrhizi in the southeast. To our knowledge, this is the first report of soybean rust caused by P. pachyrhizi on E. herbaceae. References: (1) R. S. C. Christiano and H. Scherm, Phytopathology 97:1428, 2007. (2) R. D. Frederick et al. Phytopathology 92:217, 2002. (3) S. A. Isard et al. Online publication. doi:10.1094/PHP-2006-0915-01-RV. Plant Health Progress, 2006. (4) T. L. Slaminko et al. Plant Dis. 92:767, 2008.

scholarly journals First Report of Sweet potato chlorotic stunt virus, a Component of Sweetpotato Virus Disease, in North Carolina

Plant Disease ◽  
2007 ◽  
Vol 91 (3) ◽  
pp. 327-327 ◽  
Author(s):  
J. A. Abad ◽  
E. J. Parks ◽  
S. L. New ◽  
S. Fuentes ◽  
W. Jester ◽  
...  
Keyword(s):  
United States ◽  
North Carolina ◽  
West Africa ◽  
East Africa ◽  
Sweet Potato ◽  
Virus Disease ◽  
The United States ◽  
Total Rna ◽  
First Report ◽  
Viral Sequences

Sweet potato chlorotic stunt virus (SPCSV) is the whitefly-transmitted component of the sweet potato virus disease (SPVD), a devastating disease originally described in Africa (4). Two isolates designated as G-01 and T-03 were obtained in North Carolina in July 2001 and October 2003, respectively, from plants of cv. Beauregard exhibiting symptoms typical of SPVD, including stunting, leaf narrowing and distortion, vein clearing, and chlorotic mosaic. Sap extract from symptomatic plants tested positive for SPCSV by nitrocellulose immuno-dot blot, using monoclonal antibodies specific for SPCSV obtained from the International Potato Center. Total RNA was extracted from 100 mg of symptomatic leaf tissue by using the PureLink Total RNA Purification System Kit from Invitrogen (Carlsbad, CA) with a minor modification (adding 2% PVP-40 and 1% 2-mercaptoethanol to the extraction buffer) (1). Results were confirmed by reverse transcription (RT)-PCR using primers CP1 and CP3 and HSP70-A/HSP70-B (2), corresponding to the capsid protein and ‘heat shock’ protein genes, respectively. HSP70 amplicons were cloned using the TOPO TA Cloning Kit (Invitrogen) and sequenced. At the nucleotide level, viral sequences from clones from both isolates were an average 99.4% similar to West Africa and 77.9% to East Africa sequences of SPCSV from Genbank (1). Although the isolates were collected from different fields, viral sequences generated from clones for T-03 and G-01 differed by only six nucleotides and were identical at the amino acid level. The neighbor-joining phylogenetic tree constructed using the HSP70 gene fragment (39 nt) delineated two major clusters with two subpopulations each: Cluster 1, “East Africa”, consisted of East Africa and Peru subpopulations; Cluster 2, “West Africa”, consisted of Argentina-Brazil and USA-West Africa subpopulations (1). In addition, SPCSV isolates from East Africa and West Africa clusters were sufficiently distant phylogenetically to suggest that they may correspond to two different criniviruses, with an average similarity between the populations of 78.14% and an average within the populations above 89%. Hudson's tests confirmed the presence of genetically distinct SPCSV groups with high statistical significance (1). Two groups (Peru and East Africa) were differentiated in the East Africa cluster, and three groups (Argentina-Brazil, USA, and West Africa) were differentiated in the West Africa cluster, suggesting that the USA population is not a recent introduction. Although SPCSV was previously reported in the United States, the source was a single accession of cv. White Bunch from the USDA Sweetpotato Germplasm Repository (3). Sweet potato feathery mottle virus (SPFMV) (family Potyviridae, genus Potyvirus), the other component of SPVD, was also detected in both cultivars. To our knowledge, this is the first report of SPCSV in sweetpotato fields in the United States. References: (1) J. A. Abad et al. Phytopathology (Abstr.) 96(suppl.):S1, 2006. (2) T. Alicai et al. Plant Pathol. 48:718, 1999. (3) G. Pio-Ribeiro et al. Plant Dis. 80:551, 1996. (4) G. A. Schaefer and E. R. Terry. Phytopathology 66:642, 1977.

scholarly journals First Report of Meloidogyne enterolobii on Cotton and Soybean in North Carolina, United States

Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1262-1262 ◽  
Author(s):  
W. M. Ye ◽  
S. R. Koenning ◽  
K. Zhuo ◽  
J. L. Liao
Keyword(s):  
United States ◽  
North Carolina ◽  
Dna Sequences ◽  
Natural Infection ◽  
Large Subunit ◽  
The United States ◽  
Infested Soil ◽  
First Report ◽  
Cotton Plants ◽  
Plant Pathol

Stunted cotton plants (Gossypium hirsutum L. cvs. PHY 375 WR and PHY 565 WR) from two separate fields near Goldsboro in Wayne County, North Carolina were collected by the NCDA&CS Agronomic Division nematode lab for nematode assay and identification in December 2011. The galls on cotton plants were very large in comparison with those commonly associated with Meloidogyne incognita Kofoid and White (Chitwood) infected cotton. In August 2012, the lab also received heavily galled roots of soybean (Glycine max (L.) Merr. cv. 7732) from Wayne and Johnston counties. Population densities of the 2nd-stage juveniles ranged from 150 to 3,800 per 500 cc soil. Female perineal patterns were similar to M. incognita, but PCR and DNA sequencing matched that of M. enterolobii Yang and Eisenback (4). DNA sequences of ribosomal DNA small subunit, internal transcribed spacer, large subunit domain 2 and 3, intergeneric spacer, RNA polymerase II large subunit, and histone gene H3, were found to be 100% homologous when comparing populations of M. enterolobii from North Carolina and China. Species identification was also confirmed using PCR by a species-specific SCAR primer set MK7-F/MK7-R (2). M. enterolobii Yang & Eisenback was described in 1983 from a population causing severe damage to pacara earpod tree (Enterolobium contortisiliquum (Vell.) Morong) in China (4). In 2004, M. mayaguensis Rammah & Hirschmann, a species described from Puerto Rico, was synonymized with M. enterolobii based on esterase phenotype and mitochondrial DNA sequence (3). M. enterolobii is considered to be a highly pathogenic species and has been reported from vegetables, ornamental plants, guava, and weeds in China, Africa, Central and South America, the Caribbean, and Florida in the United States (1,3,4). Of particular concern is its ability to develop on crop genotypes carrying root-knot-nematode resistance genes (Mi-1, Mh, Mir1, N, Tabasco, and Rk) in tobacco, tomato, soybean, potato, cowpea, sweet potato, and cotton. Consequently, this species was added to the European and Mediterranean Plant Protection Organization A2 Alert list in 2010. Two populations of M. enterolobii one from soybean and one from cotton were reared on tomato (Solanum lycopersicum L. var. lycopersicum) in a greenhouse setting. Eggs were extracted using NaOCl and inoculated, at a rate of 7,000 per 15-cm-diameter clay pot, into a sandy soil mixture (1:1 washed river sand and loamy sand). Tomato, peanut (Arachis hypogaea L.), cotton, watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai), pepper (Capsicum annuum L.), and root-knot-susceptible and -resistant tobacco (Nicotiana tabacum L. cvs. K326 and NC 70, respectively) were transplanted immediately into the infested soil with four replications. Root galls on the host differentials were evaluated after 90 days. Reproduction occurred on all hosts except for peanut, which is consistent with reports for M. enterolobii and M. incognita race 4 (4). Adult females from pepper plants used in the host differential test were sequenced on partial 18S and ITS1 region and confirmed to be M. enterlobii. To our knowledge, this is the first report of a natural infection of North Carolina field crops with M. enterolobii. References: (1) J. Brito et al. J. Nematol. 36:324, 2004. (2) M. S. Tigano et al. Plant Pathol. 59:1054, 2010. (3) J. Xu et al. Eur. J. Plant Pathol. 110:309, 2004. (4) B. Yang and J. D. Eisenback. J. Nematol. 15:381, 1983.

scholarly journals First Report of Stem and Root Rot of Stevia Caused by Sclerotium rolfsii in North Carolina

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 1005-1005 ◽  
Author(s):  
A. Koehler ◽  
H. Shew
Keyword(s):  
United States ◽  
North Carolina ◽  
Root Rot ◽  
Mycelial Growth ◽  
Sclerotium Rolfsii ◽  
Pathogenic Fungi ◽  
The United States ◽  
Penicillin G ◽  
Stem Tissue ◽  
First Report

Stevia (Stevia rebaundia) is an emerging crop in the United States. Once established, the crop is grown for 3 to 5 years and is typically harvested twice per growing season. Stevia leaves contain multiple glycosides that are used as a natural noncaloric sweetener that was approved by the USDA in 2008 as a sugar substitute. In commercial plantings of Stevia in North Carolina, wilting and death of plants in first- and second-year plantings were observed in 2012 and 2013. Diseased plants were observed in multiple counties in the state, with first symptoms observed in May of each year and continuing through the summer months. Prior to Stevia, these fields had been planted primarily in a corn-soybean rotation. Symptoms began as moderate to severe wilting of young shoots and chlorosis of leaves, rapidly followed by death of stems and rotting of roots. White mycelial growth was frequently observed at the base of stem tissue. Theses characteristic hyphae of Sclerotium rolfsii were often accompanied by the presence of abundant white to brown sclerotia. Isolations from infected root and stem tissue were made on potato dextrose agar amended with 50 μg/ml of streptomycin sulfate and penicillin G. Isolations from diseased tissue yielded characteristic white hyphae of S. rolfsii (1,3). Numerous sclerotia 0.5 to 2 mm in diameter developed following 4 to 7 days of mycelial growth. Sclerotia were initially white and melanized turning brown with age. To verify pathogenicity, 10-week-old Stevia seedlings were transplanted in 10-cm diameter pots containing sterile 1:1:1 sand, loam, media mix. Inoculum consisted of oat grains infested with one isolate obtained from the field plants. Oats were sterilized on three consecutive days and then inoculated with colonized agar plugs of S. rolfsii. Oats were incubated at room temperature to allow the fungus to thoroughly colonize the oats. Three infested oat grains were added to each test pot and plants were then observed over a 3-week period. Symptoms were observed within 5 days on most plants and included chlorotic leaves, bleached stems, wilting, and necrotic roots. White mycelium and abundant sclerotia were found at the base of plants. Uninoculated plants did not develop any symptoms. This is the first report of S. rolfsii on Stevia in the United States. Kamalakannan et al. (2) reported a root rot disease of Stevia in India and confirmed S. rolfsii as the causal agent. References: (1) R. Aycock. N.C. Agr. Exp. St. Tech. Bull. No. 174, 1966. (2) A. Kamalakannan et al. Plant Pathol. 56:350, 2007. (3) J. E. M. Mordue. Corticium rolfsii. CMI Descriptions of Pathogenic Fungi and Bacteria No. 410. CAB International, Wallingford, UK, 1974.

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